The present invention relates to a vehicle seat, and particularly to a vehicle seat having a mechanism for moving a headrest upon rear-end collision.
Upon occurrence of collision against a vehicle, such as an automobile, from the rear, i.e., upon occurrence of a so-called rear-end collision, it is likely that a head portion of a seating occupant is suddenly moved rearward due to inertia such that a neck portion of the occupant is likely to be subjected to an impactive shock. As such, so as to protect a head portion, neck portion, and the like, of an occupant from an impact upon rear-end collision, there has been conventionally known a vehicle seat provided with a configuration for forwardly moving a headrest upon occurrence of rear-end collision in a manner to support the head portion of the occupant to thereby mitigate an impactive shock against the neck portion (see Japanese Unexamined Patent Publication No. 2006-182094 (“the '094 Publication”), for example).
The vehicle seat described in the '094 Publication is configured to include: a plate body forwardly and rearwardly movably mounted to a backrest frame of a backrest seat; a headrest forwardly and rearwardly movably mounted to an upper portion of the backrest frame through upper links; lower links connected to the plate body and rotatably provided at a lower portion of the backrest frame; and motion transmission members for interconnecting the lower links with the upper links, respectively; such that a load sensed by the plate body upon rear-end collision is transmitted to the upper links, to move the headrest forward.
According to the above vehicle seat, it is possible to assuredly sense a rear-end collision by receiving a load upon rearward movement of an occupant due to rear-end collision, not from a back portion of the occupant, but from a vicinity of a waist portion of the occupant which exhibits a rearward displacement larger than that of the back portion. Further, the configuration for transmitting the load received by the plate body to the upper links through the lower links and motion transmission members, enables transmission of the load to the upper links with an excellent transmission efficiency, thereby ensuring a forward movement operation of the headrest.
Although the vehicle seat described in the '094 Publication is capable of assuredly sensing a load caused by a rearward movement of an occupant and received by the backrest seat, the headrest is disadvantageously moved forward, also in a situation that a load larger than that in an ordinary seating state of the occupant is applied to the backrest seat due to reasons other than rear-end collision of the vehicle, such as a situation in which the vehicle is rapidly accelerated and thus the occupant is rapidly moved rearward.